It is known that a tricyclic derivative has very strong cytotoxicity to a cancer cell line; significantly decreases a toxicity rather than colchicine or taxol injections in an animal toxicity test; significantly decreases a size and weight of tumor; and strongly suppresses an angiogenesis in HUVEC cell so that it can be used as an anticancer drug, an antiproliferative, and an angiogenesis inhibitor usefully.
Korean Patent Registration No. 0667464 discloses a method for synthesizing a compound represented by the following Chemical Formula 2 that is an important intermediate for synthesizing a tricyclic derivative compound represented by the following Chemical Formula 1:

As shown in the following Reaction Formula 4, the intermediate compound of Chemical Formula 2 is synthesized through hydrolysis, after synthesizing a compound of Chemical Formula 6, through esterification of a compound of Chemical Formula 5 and methanol, and synthesizing a compound of Chemical Formula 11 with one ester group reduced through a reduction reaction using lithium borohydride (LiBH4) as a reducing agent:

However, the preparing method of Reaction Formula 4 is not suitable to be applied to industrial production because this method uses lithium borohydride (LiBH4) as a reducing agent, which violently reacts with water to cause harmful gas and flammable gas to be generated, and also has a risk of ignition. Additionally, in the case of using sodium borohydride (NaBH4) or lithium aluminum hydride (LiAlH4) that are more easily handled as a reducing agent, there is a limitation that selectivity is decreased to thereby reduce all of two ester groups of the compound of Chemical Formula 6. Furthermore, the preparing method of Reaction Formula 4 has limitations that the compound of Chemical Formula 11 is purified using column chromatography and its yield is also very low as 58%, and when the compound of Chemical Formula 11 is purified with a re-crystallization, impurities are not completely removed and the tricyclic derivative compound of Chemical Formula 1 that is a final target compound has low purity.
Also, [European Journal of Organic Chemistry, 15, 2508(2002)] discloses a method for synthesizing an intermediate compound of Chemical Formula 2 through deprotection reaction, after preparing a solution by adding, at −78° C., sec-butyllithium and N,N,N′,N″,N″-pentamethyldiethylenetriamine to 2-fluorobenzylalcohol of Chemical Formula 13 with a hydroxy group protected and then synthesizing an intermediate of Chemical Formula 14 by adding the solution to carbon dioxide in a solid phase, as shown in the following Reaction Formula 5:

(where, R1 is methoxymethyl group or triisopropylsilyl group).
However, the preparing method of Reaction Formula 5 is not preferable in an industrial aspect because when the hydroxyl group in Chemical Formula 12 is protected with methoxymethyl group, the yield is very low as 36% and when the hydroxyl group is protected with triisopropylsilyl group, the yield is increased as 61%, but boron trifluoride diethyl etherate with strong toxicity and corrosiveness, and high risk of a fire should be used for the deprotection reaction. Furthermore, a process using sec-butyllithium with the risk of ignition is not suitable to be applied to industrial production. Also, there is no knowing as to whether a process for maintaining a reaction temperature of −78° C. to proceed a reaction and a process for dropping a solution of −75° C. to carbon dioxide in a solid phase are industrially applicable or not.
The process for preparing the tricyclic derivative compound of Chemical Formula 1 from the intermediate compound of Chemical Formula 2 is disclosed in the existing patent (Korean Patent Registration No. 0667464). However, this conventional method provides a column chromatography method as a method for purifying the intermediate compound of Chemical Formula 2, the intermediates obtained in each step, and the tricyclic derivative compound of Chemical Formula 1 that is a final product. According to this method, when the purification amount is small, the compound with high purity can be obtained; however, a large quantity of the compound cannot be purified and thus the column chromatography is not industrially suitable. Moreover, the column chromatography uses an excess amount of expensive silica gel to cause an additional industrial waste to be produced, and therefore it is uneconomical.
Therefore, while the present inventors has been conducting a study on a method for preparing the tricyclic derivative of Chemical Formula 1 in order to solve the problems of the conventional techniques, the present inventors found a high-yielding preparation method for synthesizing and purifying the compound of Chemical formula 1 with high purity from the intermediate compound of Chemical Formula 2 which was synthesized by using an intermediate prepared with a new method, and finally the inventors have completed the present invention.